PROJECT SUMMARY/ABSTRACT Conversational entrainment describes the propensity for dialogue partners to modify their behaviour to more closely align with one another. While the adaptive mechanisms underlying the tendency to entrain are not yet well understood, there is abundant evidence that entrainment is not only a robust communication phenomenon but is a crucial facilitator of successful communication, both in message comprehension and establishing personal rapport between conversational partners. Entrainment has been studied widely across many disciplines, however it has received limited attention in the field of speech pathology, where its implications may have direct clinical relevance. Problems with speech motor control interfere with the conversational rhythm, and we are just beginning to explore how this impacts measures of entrainment. We provide preliminary evidence that dysarthria disrupts speech entrainment in a simple laboratory-based reading task [1] and in face-to-face conversation [2]; and that the degree of entrainment correlates with a measure of communicative efficiency [2]. These data set the stage for investigating entrainment in the speech rhythm domain as an important variable in dysarthria, one that may have predictive or even causative effects on conversational success. This proposal aims to develop, validate, and evaluate a translational method for the study of speech entrainment in the context of dysarthria, starting with the test case of hypokinetic dysarthria and its well-documented motor limitations and deviant speech rhythm characteristics. First, we develop and validate an automated method that, exploiting tools from signal processing engineering, quantifies entrainment in task-oriented conversations between healthy participants along relevant speech rhythm features (SA1). We then evaluate the ability of our method to identify and characterize the relationship between an objective measure of communicative efficiency (joint task performance) and speech rhythm entrainment measures in the conversations between healthy participants (SA2). Finally, we evaluate our method on a set of task-oriented conversations involving partners with hypokinetic dysarthria (SA3). Successful completion of this project will demonstrate proof-of-concept for our automated method and inform the development of an R01 proposal to perform a large scale evaluation of entrainment, and meaningful clinical implications, in a broader range of dysarthria types and severities. Conversational abilities in the context of dysarthria represent a critical knowledge gap in the field, as well as a potential target for remediation that is currently not commonly addressed in clinical practice. The long-term goal of this line of work is to develop a clinical tool to assess entrainment deficits and identify potential intervention targets in the management of dysarthria. Thus, the work completed in this proposal and a subsequent R01 may allow extension of dysarthria management into the realm of conversation?advancing clinical practice and outcomes for this population.